The rongeur is a medical instrument used for a variety of purposes. It is particularly useful for removing small amounts of bone, cartilage or other body material from inside small spaces of the knee or between vertebrae. A rongeur usually includes a long fixed shank with an anvil or footplate at its distal end and a handle at its proximal end. A cross bar slideably engages the shank and reciprocates thereon by means of a pivotable second handle. Cutting edges on the distal end of the crossbar bite against the footplate to cut away a small portion of tissue with each reciprocation of the crossbar.
For precise operation of the instrument tight tolerances between the mating parts is preferred. While enhancing precise operation, these tolerances can make effective cleaning of the instrument difficult. Blood and other bodily matter with becomes trapped between the shank and crossbar can be difficult to remove. Failure to remove such matter can lead to incomplete sterilization. Accordingly, it is desirable to allow access to these parts during cleaning and sterilization.
The Janzen U.S. Pat. No. 6,126,674, incorporated herein by reference, attempts to solve this problem by providing a removable crossbar. A slot in the top of the pivotable handle receives a pin on the crossbar. A rotating disc on the fixed handle abuts a surface on the pivotable handle to limit spread between the handles. Rotation of the disc into an alternate orientation allow a slightly broader spread between the handles allowing the crossbar to move back distally off of the pin and to then be removed. In such a design it can be difficult to balance the force necessary to rotate the disc. If the force required is too great it can be difficult to operate and discourage disassembly prior to sterilization. If the force required is too low it can allow the device to disassemble accidentally during normal use.